Hi all, My 05 MINI S has had a rough idle lately then the check engine light came on last week. I checked it and got "Evaporative emissions leak no flow" cleared it and the light came back on. What could that be? Sounds like a gas cap thing to me.

Thanks,
Kyle

 

the evaporative emission system snakes all over the place in our cars. FWIW, the carbon canister, pump assembly, and a bunch of other crap are above the passenger side rear wheel well liner. Hoses go everywhere. "No flow" could be a pinched tube, or a failed emissions system vacuum pump.

FWIW, these systems are there to capture fuel vapors and send them back out as needed (so the carbon canister doesn't just fill up and stop absorbing). The vacuum pump is there to test to see if the system is sealed, as it needs to be if the carbon canister to to capture the vapors, as opposed to them leaking out. A vacuumm pump tests to see if the system is sealed, hence open gas caps or a hole in a vacuum line leading to a code. The vacuum pump can't drop the pressure in the system, and you get a code.

Matt

 

Thanks that was very helpful.

 

did you check your gas cap?

 

A gas cap would more than likely throw a leak code, not an insufficient flow code.

 

I understand the "leak" code, but not the "no flow". I'm guessing (literally) that it could be either checking the flow by opening the cannister vent solenoid or testing that the vacuum pump saw flow (put I would expect this to be listed as a failure to pressurize).